This invention generally relates to fixed-wire balloon dilatation catheters for angioplasty procedures, such as percutaneous transluminal coronary angioplasty (PTCA), and particularly to fixed-wire catheters which have little or no propensity for balloon wrapping while being advanced through a patient's vascular system.
In classic PTCA procedures, a guiding catheter having a preshaped distal tip is percutaneously introduced into the cardiovascular system of a patient and advanced therein until the preshaped distal tip thereof is disposed within the aorta adjacent the ostium of the desired coronary artery. The guiding catheter is twisted or torqued from the proximal end to turn the distal tip of the guiding catheter so that it can be guided into the coronary ostium. A dilatation catheter having a balloon on the distal end thereof and a guidewire slidably disposed within an inner lumen thereof is introduced into and advanced through the guiding catheter to its distal tip. The guidewire is first advanced out the distal tip of the guiding catheter, which is seated in the ostium of the patient's coronary artery, until the distal end of the guidewire crosses the lesion to be dilated. The dilation catheter is then advanced out of the distal tip of the guiding catheter, over the previously advanced guidewire, until the balloon on the distal extremity of the dilatation catheter is properly positioned across the lesion. Once properly positioned, the balloon is inflated to a predetermined size with radiopaque liquid at relatively high pressures (e.g., generally 4-12 atmospheres) to dilate the stenosed region of the diseased artery. The balloon is then deflated so that the dilatation catheter can be removed from the dilated stenosis and blood flow resumed therethrough.
Further details of guiding catheters, dilatation catheters, guidewires, and the like for angioplasty procedures can be found in U.S. Pat. No. 4,323,071 (Simpson-Robert); U.S. Pat. No. 4,439,185 (Lundquist); U.S. Pat. No. 4,468,224 (Enzmann et al.); U.S. Pat. No. 4,516,972 (Samson); U.S. Pat. No. 4,438,622(Samson et al.); U.S. Pat. No. 4,554,929 Samson et al.); U.S. Pat. No. 4,582,181 (Samson); U.S. Pat. No. 4,616,652 (Simpson); U.S. Pat. No. 4,638,805 (Powell); U.S. Pat. No. 4,748,986 (Morrison et al.) and U.S. Pat. No. 4,898,577 (Badger et al. ) which are hereby incorporated herein in their entirety by reference thereto.
Fixed-wire dilatation catheters with built-in guidewires or guiding elements are frequently used because the deflated profile of such catheters are generally smaller than conventional dilatation catheters having the same inflated balloon size and these catheters have greater pushability due to the guidewire being fixed therein. Further details of fixed-wire dilatation catheters may be found in U.S. Pat. Re. No. 33,166 (Samson), U.S. Pat. No. 4,619,263 (Frisbie et al.), U.S. Pat. No. 4,641,654 (Samson et al.), U.S. Pat. No. 4,664,113 (Frisbie et al.), U.S. Pat. No. 4,771,778 (Mar) and U.S. Pat. No. 4,793,350 (Mar et al.) which are hereby incorporated in their entirety by reference thereto. The lower profile of these catheters allows them to cross tighter lesions and to be advanced much deeper into a patient's coronary anatomy.
However, it has been found that the inflatable balloons of commercially available fixed-wire dilatation catheters tend to wrap on themselves as they are advanced through a patient's vascular system, particularly when torqued from the proximal end. As a result of the wrapping, the balloon frequently may not inflate completely or, if inflated, may not deflate within a desired time period. Some suppliers of such fixed-wire catheters have recommended that their catheters be limited to one rotation to avoid balloon wrapping. However, such restrictions on rotations severely limit the steerability of the catheter within a patient's vasculature.
What has been needed and heretofore unavailable is a fixed-wire dilatation catheter having a very low profile which can be torqued from the proximal end thereof without wrapping the inflatable balloon thereon. The present invention satisfies this and other needs.